1. Field of the Invention
This invention relates to a refrigerator provided with a deodorizer disposed in a circulation path for cold air so that the circulated cold air is deodorized and further to a deodorizer for deodorizing air by decomposing odor component and/or injurious matter contained in the air.
2. Description of the Related Art
In conventional household refrigerators, a platinum catalyst is disposed near a defrosting heater so that odor component contained in air is adsorbed. The heater is energized in a defrosting operation so that the adsorbed odor component is thermally decomposed, whereby the interior of the refrigerator is deodorized. However, a deodorizer providing a higher deodorizing performance has been required in order that an offensive odor in the refrigerator may be eliminated and may be prevented from scenting other food.
Recent refrigerators have been provided with two evaporators for a cold-storage compartment and a freezing compartment respectively. The humidity in the cold-storage compartment is set to be higher using the two evaporators so that an improvement is achieved in the preservation of freshness of food. However, when the humidity is increased in the cold-storage compartment, odor tends to become stronger and bacteria tend to increase.
In view of the foregoing circumstances, a deodorizer using oxidation of ozone has been equipped in refrigerators. However, odor component cannot sometimes be decomposed completely even by the oxidation of ozone such that intermediate products are produced.
Furthermore, odor component is oxidized by a photocatalyst. For example, this is achieved by irradiating ultraviolet rays onto a photocatalyst material such as titanium oxide. This method can obtain a larger oxidizing force than from ozone. However, a fluorescent lamp is required to irradiate ultraviolet rays onto the photocatalyst material. Since the fluorescent lamp contains mercury, consideration is necessary so that environmental load is not increased when the refrigerator or deodorizer is disposed of. Thus, the deodorizer employing the photocatalyst entails a problem of handling the fluorescent lamp in the case of disposition thereof.
A demand for eliminating odor component and injurious matter contained in the air in a residence has been increased with improvement in residential gastightness and chronicity in contamination of outdoor air. In particular, a demand for eliminating cigarette smoke, metabolic odor or volatile organic compound (VOC) such as formaldehyde contained in building material has been increased. The prior art has provided two major methods of eliminating odor component and injurious matter. In one method, an adsorbent such as activated charcoal is used to eliminate the odor component. In the other method, odor component is caused to react upon drugs so that the nature of the odor component is changed.
In the aforesaid first method, however, the adsorbent has a definite limit in an amount of odor component to be adsorbed. Accordingly, the adsorbent needs to be periodically replaced by a new one. Further, even before the adsorbing performance saturates, the odor component which has been once adsorbed by the adsorbent is released into air again at a final stage of the service life of the adsorbent. In the other method, the drug upon which the odor component is caused to react needs to be supplemented or replaced, resulting in complicatedness in maintenance. Further, control for adjusting the concentration of the drug released into air is difficult.
A catalytic reaction with a high deoxidation potential is required in order that an injurious gas component such as formaldehyde may be eliminated. For example, in decomposition by oxidation with use of ozone, the injurious gas component is only converted into an intermediate product due to decomposition but cannot completely be eliminated for harmlessness. Further, for example, formaldehyde or the like can be decomposed by irradiating ultraviolet rays onto a photocatalyst material such as titanium oxide. Irradiation of ultraviolet rays necessitates a fluorescent lamp. However, the fluorescent lamp contains mercury. Accordingly, a due consideration is necessary for adverse effect on environment when the fluorescent lamp is disposed of. Thus, conventional deodorizers using the fluorescent lamp entail a problem of dealing for disposition.